NPR's Peter Kenyon reports from Dohuk that Yazidi villagers and activists say extremists demanded that residents of Kocho village, about 15 miles southwest of the town of Sinjar, convert to Islam or face execution. When they refused, the men were reportedly killed.

He said reports claim that the women of the village were rounded up and the men taken outdoors and executed. Peter says estimates of the number dead range from 80 to "much higher figures."

Senior Kurdish official Hoshiyar Zebari, a former Iraqi foreign minister, told Reuters that the militants "arrived in vehicles and they started their killing" Friday afternoon. "We believe it's because of their creed: convert or be killed," the official said.

"The villagers had received local assurances that they were safe," he was quoted by The Washington Post as saying. "Maybe they killed them in revenge for the setbacks they have suffered from the [U.S.] airstrikes."

Officials warned that the Yazidis, an ancient religious minority, remain in danger despite U.S. aid drops and airstrikes launched to protect them.

In a statement from U.S. Central Command, the Pentagon said it destroyed two armed vehicles in the area where the massacre was reported.